A common means of monitoring an area is through the use of one or more closed circuit television cameras. These cameras may be connected to one or more video monitors, or a single video monitor providing a split screen function, which monitors may be observed by security personnel. The cost of having security personnel to monitor the images produced by the cameras is substantial. Further the tedium of the monitoring television images may make such monitoring unreliable.
It is known to connect the outputs of such closed circuit cameras to a video tape recorder in addition to or in lieu of providing the television signals to video monitors. Long duration video recorders using time lapse techniques can record several days worth of video input. This approach, however, provide no alarm signal but simply a record of the intrusion. If the time of the intrusion is not known, one or more videotapes must be manually reviewed, a time consuming process.
In order to minimize the recording of unimportant information, a motion sensitive video tape system may be employed where the video tape recording is activated only when motion is detected either by the camera or a separate motion detector. Such motion sensitive systems reduce the amount of video tape which must be reviewed if an intrusion is subsequently discovered, but are ineffective in areas where constant motion is to be expected. The motion sensitive devices, when connected to an alarm, tend to produce false alarms.